Maybe seeing the Star Wars ones shelfwarming for ages had stores not wanting to sit on another lot.
Or maybe it's just that game merchandise just doesn't sell, because it is a different mentality than a cartoon or movie that has toys... in that people just play the game to fill time or a bit of fun, but don't have enough attachment to the concept to want to buy too many "souvenirs" of it, if at all.
I see a LOT of Minecraft merchandise in stores, but don't see much of it moving. They look fascinating and surreal in person, but not interesting enough to want to spend money on it as a non-player of the game... and unless you spend an obsessively unhealthy amount of time on the game to become a fan, I don't imagine too many people would buy much of the merchandise.